The AB Game is a code-breaking game where the codebreaker tries to guess the codemaker's secret code.

• The secret code is a sequence of 4 unique digits (0-9).
• After each guess, the codemaker provides a hint:
  • "A" indicates a correct digit in the correct position.
  • "B" indicates a correct digit in the wrong position.
• The hint format is "xAyB", where:
  • "x" is the number of correct digits in the correct position (A).
  • "y" is the number of correct digits in the wrong position (B).

For example, if the secret code is "1234" and the guess is "1327", the hint would be "1A2B".